func calculateHash(reference *etree.Element, doc *etree.Document) (string, error) {
digestMethodElement := reference.SelectElement("DigestMethod")
if digestMethodElement == nil {
return "", errors.New("signedxml: unable to find DigestMethod")
}
digestMethodURI := digestMethodElement.SelectAttrValue("Algorithm", "")
if digestMethodURI == "" {
return "", errors.New("signedxml: unable to find Algorithm in DigestMethod")
}
digestAlgo, ok := hashAlgorithms[digestMethodURI]
if !ok {
return "", fmt.Errorf("signedxml: unable to find matching hash"+
"algorithm for %s in hashAlgorithms", digestMethodURI)
}
doc.WriteSettings.CanonicalEndTags = true
doc.WriteSettings.CanonicalText = true
doc.WriteSettings.CanonicalAttrVal = true
h := digestAlgo.New()
docBytes, err := doc.WriteToBytes()
if err != nil {
return "", err
}
//ioutil.WriteFile("C:/Temp/SignedXML/Suspect.xml", docBytes, 0644)
//s, _ := doc.WriteToString()
//logger.Println(s)
h.Write(docBytes)
d := h.Sum(nil)
calculatedValue := base64.StdEncoding.EncodeToString(d)
return calculatedValue, nil
}
